arduous /ärˈdū-əs/

1. Steep, difficult to climb
2. Difficult to accomplish
3. Laborious

ardˈuously adverb

• setae
• set against
• setal
• set alight
• set apart
• set aside
• set-aside
• set-asides
• set-aside scheme
• set a sponge
• set at naught
• set at nought
• set back
• setback
• set back on one's heels
• setbacks
• set by
• set by the ears
• set by the heels
• set dancing
• set down
• set-down
• set-downs
• se-tenant
• set eyes on